TTC with low sex drive husband

My husband has a very low libido - he was celibate for most of his life before we met and he’d be ok if we never had sex again. But we’re trying to start our family. The most I can get him to have sex is once a week at most (and in the morning), so when is the best time if we’re TTC? The day before ovulation? Day of? My cycle is very regular, but we are 34 and 43 years old.